This invention relates to certain pyrrole derivatives, specifically, to certain 2-(imidazol-1-ylmethyl)pyrroles, and to their use in selectively inhibiting the action of the thromboxane synthetase enzyme, i.e. without significantly inhibiting the action of the prostacyclin synthetase or cyclo-oxygenase enzyme. The compounds may thus be useful in, for example, the treatment of ischaemic heart disease, stroke, transient ischaemic attack, migraine and the vascular complications of diabetes.